3Com Switch 8800 Configuration Guide Chapter 38 MSTP Region-configuration38-29By default, the parameter is configured as auto.38.2.15 Configuring the mCheck Variable of a PortThe port of an MSTP switch operates in either STP-compatible or MSTP mode.Suppose a port of an MSTP switch on a switching network is connected to an STPswitch, the port will automatically transit to operate in STP-compatible mode. However,the port stays in STP-compatible mode and cannot automatically transit back to MSTPmode when the STP switch is removed. In this case, you can perform mCheckoperation to transit the port to MSTP mode by force.You can use the following measure to perform mCheck operation on a port.I. Configuration in system viewPerform the following configuration in system view.Table 38-24 Configure the mCheck variable of a portOperation CommandPerform mCheck operation on a port. stp interface interface-list mcheckNote:By default, MSTP runs in MSTP mode, which is compatible with RSTP and STP (Thismode can recognize MSTP BPDU, STP config BPDU and RSTP config BPDU).However, the STP switch can only recognize config BPDU (STP BPDU) sent by theSTP and RSTP bridges. After the switch running STP-compatible mode switches backto MSTP mode, it will not send MSTP BPDU if you do not execute the stp mcheckcommand. Therefore, the connected device still sends config BPDU (STP BPDU) to it,causing the same configuration exists in different regions and other problems.Remember to perform stp interface mcheck after modifying stp mode.II. Configuration in Ethernet port viewPerform the following configuration in Ethernet port view.Table 38-25 Configure the mCheck variable of a portOperation CommandPerform mCheck operation on a port. stp mcheck
